The present invention relates to a laser ablation apparatus which is used to form a film of a compound utilized for a thin film device.
A conventional laser ablation apparatus (disclosed in "PRACTICAL SUCCESS OF CERAMICS DEPOSITION APPARATUS BY THE USE OF LASER" in "Machines and Tools" by Atsushi Ohmine, issued on July 1990, pages 2-6) will be depicted hereinbelow with reference to FIG. 7.
In the conventional laser ablation apparatus of FIG. 7, when a laser light 22 of an energy density not smaller than a threshold value is cast to a rotary cylindrical target 21 in vacuum chamber 26, a material 23 that flies from the target 21 is adhered to a substrate 24. The laser light used is generally a pulse laser light of a short wavelength. The laser light 22 is projected to the target 21 through a sealed window 25 after being condensed to a high energy density. The substrate 24 is disposed inside the vacuum chamber 26.
In the aforementioned prior art, when a film is to be formed on a large-area substrate, it is necessary to move the substrate 24 because of the fact that an evaporation spot is small, and a vacuum chamber of a size not smaller than four times the substrate is needed. Moreover, since the evaporated particles adhere to the window 25, the laser power is decreased on the target 21.